Cement and process of making same



Patented J l; 6,.

palm STATES lio Drawing.

A difiicultyin the area alumina cement processes invented by Jules .Bied (patented .is desirable) it is necessary to start with very low-silica rawmaterials. I In the process now described this difiicu'lty is obviated bycarrying out thb fusion in a strongly reducing atmosphere and in the presence of sufficlent free carbon to reduce to the metallic state not merely the bulk of the iron oxide present in the raw materials, but also such portion of the silica as may be desired.

In carrying out this process, a mixture of suitable raw materials, for example iron ore, limestone and bauxite-or -iron ore, limestone and high alumina claysis fused in a blast or electric furnace. Suflicient carbon is added, in'the form of coke, charcoal, etc, not merel to supply the heat necessary for .smelting ut to reduce the iron oxide and such portion of the silica as may be desired. The two reduced metals unite in the meltingzone to form ferro-silicon--which is in'itself a highly valuable productthus sharply reducing the costs of the alumina cement itself, which is made from the sla Y The raw materials possible are numerous, and may be combined in many. ways. The essential features of calculating the charge are: r

(1) That the lime and alumina present must be in such relative proportions-that the chemical compound 5CaO,3Al,Q may be formed.

carbon to. reduce the iron oxide and ,sil-

ica to such extent that not over-5% of fer- IOHS QXIdO and I notover of silica remam in the slag.

(3) That there must be suflicient iron present, relative to the silica to be reduced; ture of mateg als containing alumina, iron, 0 I

so that the economic. formation of 'ferrd-silicon (or of a high-silicon pig) ispossible.

PATENT AQFFICEIT;

'nnwnt 'o. noun, orwasnnm'rong manner or commma.'

- 0151mm um Promise or naxmo sum.

Application med larch 31,1926. 7 Serial No. 98,981.

For blast furnace use such an economic ferro-silicon may carry from 10% to of silicon withfrom 90% to 75% metallic iron; while if the electric furnace, be employed the ferro-silicon may economically carry as much as 25 to of silicon as against 75% to' of iron.

vBy .use of the process herein described, it is technically and economically possible to utilize bauxites high in silica, as well asother' highly siliceous materials not heretofore em ployed such as siliceous'diaspore clays, and even clays of the type of kaolinite and halloysite, heretofore unuseable by any process everemployed or even suggested for use. An inciden l advantage is that the resence ofthe high percentages of iron an of free or excess carbon makes'it easily possible to produce fused lime-alumina cements whose essential component is the compound 509,0,-

3Al O giving higher strengths and greater durability than the mono-calcic compounds previously em loyed in the Daher, Mellersh J 'ackson and afarge processes. 7

The presence of unreduced silica results in the formation of a relatively small amount oflime silicate in the cement slag;

and at times a still smaller percentage of ferrous silicate is similarlyproduced, whereby the resulting cement composition will be approximately I claim:

1. The process ofmaking alumina cement and ferro-silicon by the fusion of a mixture of raw materials containing alumina, iron oxide, silica and lime, in the presence of suf- ,ficient free carbon to reduce most of the iron Y 2. The process of making cement and fer-i ro silicon'comprising the fusion of a mixsilica and lime, in the presenceof sufiicient free carbon to form ferro-silicon.

3. The process of making cement andferro-silico n comprising the fusion of a cement ro-silicon comprising the fusion of a cement forming mixture containing iron and silica, forming mixture containing iron and silica in the presence of suflicient free carbon to in the presence of sufiicient free carbon to form high-silicon-pig iron and cement slag.

fi'ffrm commercial ferro-silicon and cement In testimony whereofllafiix my signature.

s ag. r

4: The process of making cement and fer- EDWIN C. ECKEL. 

